Consider adding connection Activities to RabbitMQActivitySource

[eerhardt]

Is your feature request related to a problem? Please describe.

It is hard to diagnose an application that is failing because its RabbitMQ server is unavailable, or an existing connection is terminated and reconnects start happening.

Describe the solution you'd like

In order to be able to diagnose connection problems in applications, we should add an Activity when a connection is attempted to be established, and set the exception on the Activity when it fails. This also applies to auto-recovering channels.

Describe alternatives you've considered

No response

Additional context

In .NET Aspire's RabbitMQ integration we added an Activity for each connection attempt when calling IConnectionFactory.CreateConnection. This allows developers to see the connection attempts in their telemetry sink (for example the .NET Aspire Dashboard).

It would be great if this was moved into the official RabbitMQ.Client library for all apps to be able to use, not just when using the .NET Aspire integration.

cc @lukebakken @stebet

[lukebakken]

Feel free to open a PR, thanks.